To complete the chromosome studies on the effects of gamate aging on pig blastocysts. To begin the chromosome studies on the effects of elevated maternal body temperature on pig blastocysts. To continue to investigate the factors responsible for the failure to recover the expected number of blastocysts at 14 days from superovulated cows and to continue the base line chromosome studies on bovine blastocysts. These studies will be expanded to study the effect of sex steroid hormones on embryonic mortality in conjunction with Dr. V. K. Ganjam. To continue chromosome studies on spontaneous abortuses and cogenital malformation as material becomes available. To continue to perfect differential staining techniques for the identification of specific chromosomes from animals. To continue analyses of meiotic chromosomes including differential staining techniques.